<template>
  <div>
      <h1>当前求和为：{{sum}}</h1> 
      <select v-model.number="n">
        <option value="1">1</option>
        <option value="2">2</option>
        <option value="3">3</option>
      </select>
      <button @click="increment">+</button>
      <button @click="decrement">-</button>
      <button @click="incrementOdd">当前求和为奇数再加</button>
      <button @click="incrementWait">等一等再加</button>
  </div>
</template>

<script>
    export default {
        name:'Count',
        data() {
            return {
                n:1,     //用户选择的数字
                sum:0,   //当前的和
            }
        },
        methods: {
            increment(){
                this.sum += this.n
            },

            decrement(){
                this.sum -= this.n
            },

            incrementOdd(){
                if(this.sum % 2){
                    this.sum += this.n
                }
            },

            incrementWait(){
                setTimeout(() => {
                    this.sum += this.n

                },500)
            }
        },
    }
</script>

<style>
    button {
        margin-left: 5px;
    }
</style>
